Nuclear-grade nickel-chromium-iron alloy welding wire as well as preparation method and application thereof

Abstract

The invention discloses a nuclear-grade nickel-chromium-iron alloy welding wire as well as a preparation method and application thereof, the nuclear-grade nickel-chromium-iron alloy welding wire is prepared by designing alloy components, adopting matched processes such as vacuum induction smelting, electroslag remelting, forging, rolling and drawing and controlling process parameters in each process, so that the nuclear-grade nickel-chromium-iron alloy welding wire is ensured to have good welding manufacturability; the welding process is stable, splashing is avoided, fluidity is good, a weld bead is attractive and smooth, slag inclusion, air holes, cracks and other macroscopic defects and microscopic cracks are avoided, weld metal components meet the requirements, excellent obdurability is achieved, and the welding performance requirement of nuclear energy equipment is met.

Description

technical field [0001] The invention relates to the technical field of welding materials, in particular to nuclear-grade nickel-chromium-iron alloy welding wire and its preparation method and application. It is suitable for welding key components of nuclear islands with radiation resistance, stress corrosion resistance and high temperature resistance, and can be used for welding nickel-based alloys, nickel Base alloy and low alloy steel dissimilar metal welding and surface surfacing, etc. Background technique [0002] Nuclear energy is an important clean energy source. Vigorously developing nuclear power has become an important measure to save energy, reduce emissions, and reduce pollution, which is of great strategic significance; due to the long-term Working in a variety of harsh environments such as high temperature, high pressure, corrosion, dynamic load and radiation, once leakage or other accidents occur, the consequences will be very serious; in order to ensure the sa...

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Problems solved by technology

[0002]Nuclear energy is an important clean energy, and vigorously developing nuclear power has become an important measure for energy saving, emission reduction, and pollution reduction, and has important strategic significance; Key equipment such as pressure vessels, steam generators, voltage stabilizers, etc. have been working for a long time under the conditions of high temperature, high pressure, corrosion, dynamic load, radiation and other harsh environments. Once an accident such as leakage occurs, the consequences will be very serious; to ensure The safety of the structure has high requirements for welded joints, so the requirements for the welding materials used are almost strict; because nickel-based alloys and their welding materials have excellent mechanical properties, environmental service performance and weldability, etc., so its It is widely used in key components and welding consumables in the primary circuit system of nuclear power plants, but due to its own material characteristics, it is prone to crystallization cracks, liquefaction cracks, high-temperature plastic loss cracks, and corrosion tendency in the welding zone during welding. Insufficient, although most of the problems have been solved through technical progress such as composition adjustment and welding process improvement, but many years of application practice have proved that there are still many problems in the nuclear-grade nickel-based alloy welding materials that have been commercialized in the world, and the welding process is not good. Oxidation resistance is poor, strong-plastic fit is poor, weld metal thermal cracks and high-temperature plastic loss cracks tend to be more serious, especially reheat cracks often occur during multi-layer and multi-pass welding of thick welds, which not only increases the difficulty of welding construction, Moreover, it is difficult to ensure the long-term safe operation of nuclear power plants, and the international community is still in the stage of continuous research and improvement; therefore, the development of nuclear-grade nickel-based alloy welding materials with its own intellectual property rights is the only way for the long-term development of nuclear power, and it is also the basic guarantee for national energy strategy security. ;

[0003]Currently regarding nuclear-grade nickel-based alloy welding materials, it is mainly by adding certain alloy elements to try to improve the above deficiencies. Early patents add Al, Ti elements or Mn, Nb elements are used to improve weldability and weld metal strength. In recent years, by adding Mo and W elements and further increasing Nb elements to improve the tendency of hot cracks and high-temperature plastic loss cracks, and even by adding B to improve ductility crack resistance, by adding Mg, Ca and Zr refine grains and improve welding surface quality; however, the addition of the above elements brings great difficulties to metallurgical technology and thermal processing technology, such as: Mo and W have high density and high melting point, and are easy to segregate during smelting , resulting in uneven welding material quality, and easy to form coarse M2C type and M6C type liquid precipitation carbides, which greatly reduces the thermoplasticity of the alloy and increases the welding process Crack tendency caused by repeated heating-cooling cycles; Mg, Ca, and Zr are easily oxidized, and easily aggregate and grow with the oxides of deoxidized elements Al and Ti in welding to form inclusions, and then form point defects; and B elements are medium Sub-absorbents, which will affect nuclear reactions, are strictly limited in nuclear island equipment

Therefore, the addition of the above-mentioned alloying elements greatly increases the manufacturing difficulty of welding wire such as smelting and rolling, making it difficult to control the quality of welding consumables stably, so that the welding quality is also in a state of fluctuation. More importantly, the addition of the above-mentioned alloying elements has not completely changed Poor welding processability, poor oxidation resistance, poor strong-plastic fit, severe tendencies of weld metal hot cracks and high-temperature plastic loss cracks, and reheat cracks are prone to occur in multi-layer and multi-pass welding of thick welds

In the prior art, for example, U.S. Patent US6242113 (B1) discloses a welding alloy, which includes the following components by weight percentage: C: 0.005-0.05%, Mn: ≤1.0%, Fe: 7.0-11.0%, P: ≤ 0.02%, S: ≤0.01%, Si: ≤0.05%, Cu: ≤0.2%, Al: 0.01-0.25%, Ti: 0.01-0.35%, Cr: 27.0-31.5%, Nb: 0.60-0.95%, Mo : ≤1.0%, Co: ≤0.12%, Zr: ≤0.10%, B: ≤0.01%, W: ≤1.0%, the patent strengthens the alloy by Mo, Nb, B, Zr and controls the carbide morphology to strengthen the alloy, The tendency of solidification and cracking during alloy welding is reduced by controlling the lower Al, Ti, Mn, and Si contents, but the alloy element Zr in this patent has a strong affinity with oxygen, and it is easy to form point-like oxide inclusions during the smelting process. The Mo element has a large proportion and is easy to form segregation, resulting in uneven alloy composition, and the restrictions on Co and B are not strict, so it is not suitable for use in nuclear radiation environments. In addition, the patent does not disclose the preparation method; EU patent WO2016081940 discloses a welding alloy. Including the following components by weight percentage: C: 0.040-0.09%, Mn: ≤1.0%, Fe: 1.0-16.0%, P: ≤0.02%, S: ≤0.015%, Si: 0.0010-0.5%, Cu: ≤1.0%, Al: 0.001-0.50%, Ti: ≤0.5%, Cr: 28.0-31.5%, Nb: ≥0.60%, Mo: 1.0-7.0%, Co: ≤0.20%, Zr: ≤0.020%, B : ≤0.015%, W: ≤1.0%, Ca: ≤0.10%, Mg: ≤0.02%, impurity ≤0.5%, the patent is mainly by adding a large amount of Mo (1.0~7.0%), Nb+Ta (2.2~4.0 %) and a certain amount of W to strengthen the alloy, improve the sensitivity to high temperature loss of plastic (DDC) and stress corrosion resistance, but adding a large amount of high-density Mo, Ta, W elements can easily cause uneven distribution of alloy components, and extremely It is easy to crack and brings great difficulties to thermal processing and manufacturing. At the same time, adding a certain amount of Ca and Mg elements for deoxidation and desulfurization will form point defects such as inclusions, which will affect the performance of the weld. Also, the patent does not disclose the preparation method;

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